The fabrication of small devices often entails bringing two or more surfaces into contact with highly precise alignment criteria. By way of example, nanoimprint lithography involves bringing a mold into contact with a substrate to imprint a pattern thereon, with precision alignment becoming especially important when new patterns are to be imprinted upon a substrate having previously-imprinted patterns. Alignment issues can arise from dimensional changes in the substrate, such as those brought about by temperature changes or other intrinsic or extrinsic causes. By way of example, a substrate imprinted with a first mold at a target location might experience a thermally-induced dimension change prior to application of a second imprint mold, which may cause that target location to shift slightly. Even if the second mold is positioned exactly where the first mold was positioned in the imprinting system, there may be an undesired misalignment between the second imprinted pattern and the first imprinted pattern on the substrate.
It would be desirable to provide for precise determination of a dimensional change undergone by a surface. It would be further desirable to determine such dimensional change in a non-invasive manner. It would be still further desirable to determine such dimensional change in a manner that does not require the existence of alignment markers or similar landmarks on the surface undergoing the dimensional change.